Arrangement in sail sheets



May 1941. H. T. H. ANDRESEN 2,240,878

ARRANGEMENT IN SAIL' SHEETS Filed Jan. 9, 19:59

INVEN 'R Patented May 6, 1941 ARRANGEBEENT KN SAIL. SHEETS V Halvor Tobias Heyerdah'liand resen, Gislc,

Norway Application January 9, isaaseriai No. 256,051 In Norway August S0; 1938 (C1. lid-402) 7 Claims.

The present invention relates to surfaces made of cloth, fabric, leather or the like, which surfaces are to be suspended from a tightened forward leech, a mast, boom, taut rope or wire or the like, in such a manner that a movement of the surface is eifected when the same is subjected to the influence of an air flow, or a deflection of an air flow effected by the surface when the same is moved relatively to the said air flow, the surface thereby under all conditions adopting the setting: most favorable for its purpose.

Inthe following specification and claims the term surface is intended to cover all kinds of suspended surfaces, such as sails, propeller or windmill wings or carrying wings for gliders and the like, by which surfaces the satisfactory action depends upon a correct setting and curve of the surface against the reaction (pressure) of the air flow;

Such surfaces which are suspended or stretched from a fixed forward leech, for instance a meet, a foresail stay or the like, will due to. the reactions of the air flow; which appear as pressure on the wind side of the surface and partly" as suction on the lee side, assume a curved form. In usual sails, this form is not the most favorable in respect of obtaining a high efficiency over the entire sail area. Usually sails are made with a certain concavity or tailoring in order to obtain a favorable form at least over a certain portion of the sail area. This tailoring is, however, gradually changed by the stretching or tightening forces from a boom or from corners in the sail, with the result that the sail form will be in the main unfavorable.

According to know aerodynamic principles, the most favorable surface form is a curved one in which the greatest convexity is near to the fixed forward edge, where also the greatest reactions of the air now appear.

According to the present invention, the surface is tightened or stretched by means of a line systent in which the lines are running through rings, blocks or the like in such a manner that the tightening force transmitted by the said system, is distributed to points spaced along the greater part of the aft leech of the surface and one or more spaced points located in the surface area inside of the said aft leech. The degree of distribution or splitting up of the forces in each particular case, of course must be in a practical relation to the increase in efiiciency thereby obtainable.

In smaller surfaces such as for instance small sails in which the sheet arrangement should be as simple as possible, and in which the stretching or tightening force (the sheet) may be derived from one or morepoints at a reasonable distance from the aft leech of the surface, a high efficiency may be obtained by distributing the stretching force for instance to three spaced points in laps in the aft leech of the sail, such as described in my U. S. A. Patent No. 2,151,368. By larger, surfaces, such as for instance large sails, or when the stretching force of the surface is derived from one ormore spaced points, a comparatively short distance from the aft leech of the surface, it is favorable to apply a great part of the distributed stretching force to the surface inside of the aft leech, nearer to the portion of the surface area in which the greatest reactions of the air flow against the surface appear, or even secured to the forward leech of the surface. The stretching force thereby will be more directly transmitted to the portion of the surface where the same carries the pressure of the air flow, andmust not be transmitted through the aft portions of the surface, which a way serve mainly as a guiding surface for the air flow, when the same has accomplished its actionon the foremost portion of the surface, whereby a smaller portion of the stretching forces is required for holding the said aft portions of the surface in a correct positionin the air flow.

Due to the fact that. each of the lines forming the line system transmitting the distributed stretching force is secured to the surface ina plurality of spaced points by running through a system of. rings, blocks or the like, there will be such mutual relation: between the forces transmitted by the individual parts of each line, and between; these forces and the area of the port on of the surface to be held in position against the air flow by the individual line part, that each particular line part transmits such portion of the total force transmitted by the line system, that the portion of the surface corresponding to each articular line gets an efficient angle and curvaturein the air flow. All the main lines formin the system, or some of them, may suitably be combined in-one continuous line. In this manner the lines will co-operat'e all over the surface so as to hold the same in a form giving a favorable efficiency. This line system as a matter of fact. automatically brings about a correct adjustment of the form of the surface when the sheet (the main. force) is tightened or slackened.

Instead of directly securing each individual line of the line system to the surface in the above described manner, the lines may, through rings, blocks or -the like, be connected to one or more separate subordinate lines secured to the surface by running through a system of rings or the like similar to the system above described.

The parts of the lines or of the sublines secured to the points in the surface located in the innermost portion of the same may suitably be sewed into the surface or they may be carried through a pocket in the surface. Such pockets may be made conical, each pocket surrounding one particular line, or they may be made as bigger pockets, each receiving a number of lines. If desired, the pocket walls may, in a manner known per se, be apertured for the stabilisation of the surface around the lines, or the surface may be provided with slots adjacent to the pocket and parallel to the main direction of the same or to the line part, sewed into the surface, one of the parts of the lines or sublines then being secured to the free lap of the surface on the oppositeside of the slot, and the other part or parts of the line being secured to a point or more spaced points along the edge of the surface at or near to the other side of the pocket or the line part, sewed into the surface.

The appearance of an arrangement according to the invention is on the whole as a number of lines, running through rings or blocks, some of the lines reaching towards the front leech, and so in a way also carrying the surface, and some of the lines stretching on other leeches, all lines being interconnected and pulled from the main sheet which holds the surface in the desired position. v

In the accompanying drawing some embodiments of the invention as applied to sails and carrying wings for gliders, are shown diagrammatically.

Figures 1 and 2 are side views of different arrangements in accordance with the invention, applied to sails;

Figs. 3 and 4 are side views on a larger scale of arrangements for tightening or stretching lines.

In Figure 1, I designates a sail suspended between a mast 2 and a block or ring 3 by means of a sheet 4 running through the ring 3. By means of a system of rings or blocks 5, B the stretching force of the line 4 is distributed to the lines I, 8 wherefromthe stretching forces by means of further rings or blocks 9, I 0, are distributed to further lines or line systems l3, l4, secured to the sail surface at spaced points in the sail or along the greater part of the aft leech of the sail, such as IE, or is run on one side of the sail surface, through a ring in the same and back on the opposite side of the sail surface.

By different runnings of the lines it is possible, in a manner known per se, to obtain an arrangement in which each particular line transmits exactly such portion of the total stretching force that each particular portion of the sail surface assumes an efiicient position in the air flow,

Obviously the points in which the sublines are secured to the surface may be distributed in other suitable manner than shown in Fig. 1. Thus, the lines running from the ring or block such as H! in Fig. 1, are secured to points inside of the aft leech of the sail and at different distances from the same. How far the distribution of the stretching force and of the securing points of the sublines to the sail is to be carried, depends on the increase in efficiency thereby obtainable.

The sublines secured at points forward of the aft leech may, for instance, be secured at one side of the sail I, whereby the sail will adopt a different standing according to the side from which the air flow comes, the surface leaning against the lines when the wind is from the side of the sail, opposite to that at which the lines are secured. By running of the lines forwards on one side and backwards to the other side of the sail surface, as shown in Fig. 1, or by making the sail surface double from a line through the innermost securing point and backwards, a sail of equal standing may be obtained.

In Figure 2 a sail l is shown, which is suspended between a mast 2 and an auxiliary mast 20, by means of a line 4 running through rings or blocks 3 secured to the mast 20. By means of rings or blocks 9, Ill and H the stretching force from the line 4 is distributed to further lines or line systems [3, l4 and 15 secured to the sail surface at or inside ofthe aft edge (leech) of the sailsurface. In the embodiment shown the sublines l3, I4 and I5 are running through fpockets 2|, 22in the aft portion of the sail, whereby the sail will adopt equal standing under wind pressure from both sides. The pocket 22 is shown apertured by 23 for stabilisation of the sides of the pocket. 7

Figure 3 is a view of an arrangement of a line system similar to that shown at [3 in Figure 1, but applied to the sail above the bottom edge of the same, and in which the line part I3 is sewed in at one edge of a slot 24, the line part l3 running from the inner end 29 of the slot 24 to a point 28 in which the line is divided into two parts I3", each of which runs through the ring It! to the aft leech of the sail at 25 and 26 respectively, on opposite sides of the slot 24.

' Fig. 4 is a view of a subline arrangement wherein line l4 runs thru a ring In, a second ring l0 sewed into the sail I and from the second ring I0 back along the opposite side of the sail to the ring I0 where it is secured. Another line l5, secured tothe after leech of the sail at spaced points IS, I6, is rove thru ring l0 so that its middle or bight portion is free to slide therein.

What I claim is:

1. An air flow device having a surface supported at its forward edge and spread so as to react to airflow, in combination with stretching means connected thereto, said stretching means comprising a plurality of lead lines connected with points distributed along the after edge of said surface and forward of the same, and an adjustable main sheet associated with said lead lines, whereby adjustment of said lead lines is accomplished simultaneously with an adjustment of the main sheet.'

2. An air flow device having a surface supported at its forward edge and spread so as to react to air flow, in combination with stretching mean connected thereto, said stretching means comprising a plurality of lead lines connected with points distributed along the after edge of said surface and forward of'the same, an adjustable main sheet associated with said lead lines, and guide mean for said main sheet, whereby adjustment of said lead lines is accomplished simultaneously with an adjustment of the main sheet.

3. An air flow device having a surface supported at its forward edge and spread so as to react to air flow, in combination with stretching means connected thereto, said stretching means comprising a plurality of lead lines connected with points distributed along the after edge of a in. r

said surface and forward of the same, an adjustable main sheet in slidable connection with said lead lines, and guide means for said main whereby adjustment of said lead lines is accomplished simultaneously with an adjustment of the main sheet.

4. An air flow device having a surface supported at its forward edge and spread so as to react to air flow, in combination with stretching means connected thereto, said stretching means comprising a plurality of lead lines connected with points distributed along the after edge of said surface and forward of the same, a main sheet connected with said lead lines, and means for so guiding said main sheet that each individual line of said plurality of lead lines may adopt a setting corresponding to the air flow forces on that portion of the surface which the line controls.

5. An air flow device having a surface supported at its forward edge and spread so as to react to air flow, in combination with stretching means connected thereto, said stretching means comprising a plurality of lead lines connected with points distributed along the after edge of said surface and forward of the same, a main sheet connected with said lead lines, and a system of blocks and pulleys through which said main sheet is adjustable, whereby for a given adjustment of the main sheet the said lead lines will adopt a setting corresponding to the air flow forces on the portions of said surface carried by each individual line.

sheet,

6. An air flow device having a surface supported at its forward edge and spread so as to react to air flow, in combination with stretching means connected thereto, said stretching means comprising a plurality of lead lines each of which is connected with a point along the after edge of said surface and with a point forward of the same, an adjustable main sheet, rings threaded upon said lead lines and connected with the main sheet, and mean for so guiding said main sheet that each individual line of said plurality of lead lines may adopt a setting corresponding to the air flow forces on that portion of the surface which the line controls.

7. An air flow device having a surface supported at its forward edge and spread so as to react to air flow, in combination with stretching means connected thereto, said stretching means comprising a plurality of lead lines connected with points distributed along the after edge of said surface and in pockets forward of said after edge of said surface, an adjustable main sheet associated with said lead lines, and means for so guiding said main sheet that each individual line of said plurality of lead lines may adopt a setting corresponding to the air flow forces on that portion of the surface which the line controls.

HALVOR TOBIAS HEYERDAHL ANDRESEN. 

